XDS-23 is a selective biofilm inhibitor with an IC50 value of 1.26 µM against Pseudomonas aeruginosa. It exhibits dual inhibitory effects on the LasI/LasR system and the Pseudomonas Quinolone Signal system, suppressing key virulence factors such as elastase, pyocyanin, and extracellular polysaccharides. In both in vitro and in vivo models, XDS-23 demonstrates synergistic antibacterial activity, enhancing the efficacy of various antibiotics with good safety profile. XDS-23 is applicable for research related to treating biofilm-mediated resistant Pseudomonas aeruginosa infections.

XDS-23, at concentrations of 0.3125-5 μM over 24 hours, significantly inhibits the formation of Pseudomonas aeruginosa PAO1 biofilms, reducing biofilm biomass by up to 60% at 5 μM without affecting planktonic bacterial growth. It decreases the number of viable cells within biofilms and suppresses extracellular polysaccharide synthesis, exhibiting an inhibition rate of up to 50% at 5 μM, ultimately leading to thinner and structurally compromised biofilms. XDS-23 also suppresses the production of pyocyanin and elastase in a concentration-dependent manner, achieving inhibition rates of 70% and 50% respectively at 5 μM. It shows broad-spectrum inhibitory activity against clinical multidrug-resistant Pseudomonas aeruginosa isolates, with notable inhibition, including nearly 50% for PA0617 and PA1065, and around 44.87%, 34.89%, 33.56%, and 36.80% for PA0808, PA1129, PA1074, and PA1167, respectively. Furthermore, XDS-23 decreases pyocyanin secretion in all clinical isolates except PA1031, with inhibition rates exceeding 30% for PA0808, PA0617, and PA1074. The compound primarily reduces biofilm formation and virulence factor production by inhibiting the las and pqs systems of Pseudomonas aeruginosa PAO1. At 5 μM over 24 hours, XDS-23 impairs the motility of Pseudomonas aeruginosa in a concentration-dependent manner: swarming is reduced by 60%, twitching by 50%, and swimming by 30%. When combined with Polymyxin B (PMB), Ciprofloxacin (CIP), Ceftazidime (CAZ), and Tobramycin (Tob), XDS-23 (0.3125-5 μM, 24 hours) decreases bacterial load in Pseudomonas aeruginosa PAO1. In human liver cancer cells (HepG2), XDS-23 (6.25-100 μM, 24 hours) exhibits no significant cytotoxicity， and it shows no hemolytic activity against rabbit erythrocytes at concentrations of 1.25-40 μM over 4 hours.

The compound XDS-23, administered via hemocoelic injection at doses ranging from 6.25 to 100 μM (5 μL volume, single dose), demonstrates good preliminary safety in a Galleria mellonella larvae model, with no mortality observed. Furthermore, XDS-23 at 0.052 mg/kg (single hemocoelic injection) enhances the therapeutic efficacy of Polymyxin B, Ciprofloxacin, Ceftazidime, and Tobramycin against P. aeruginosa PAO1 infection in the larvae.